This invention relates to lubricating oil compositions and more particularly to a lubricating oil composition for hi-performance gasoline and diesel engines.
The conventional zinc dithiophosphates used as antiwear lubricants in engine oils do not provide adequate camshaft and valve train wear protection on exposure to severe environment of modern high performance turbocharged engines.
One of the problems involved in the engines is the wear on moving parts. The highest source of engine wear is generally valve train wear (VTW). This is particularly true on engines which have sliding contact between the camshaft lobes and the lifters or followers. Engine oil additives, particularly antiwear additives, are the primary source of preventing excessive VTW. There are many different engine valve train designs and metallurgies in use, which have somewhat different wear characteristics. Also, wear is affected by engine operating condition. Many VTW tests use higher-than-normal valve spring loads and/or special metallurgy wear parts to achieve good wear discrimination in a reasonable length test.
As a result, there are many different VTW tests in use. There are standard VTW tests which provide the wear protection requirements for engine oil performance categories. In addition, some engine manufacturers have their own VTW tests which they require before they approve an oil for use in their engines. Most VTW tests are difficult enough that engine oils must be carefully formulated to achieve both sufficient wear protection and economical additive cost.
Thus, of the present invention is to provide a lubricant additive which will prevent wear in moving parts in a high performance turbocharged engine, including the camshaft and valve train of such engines.